Sir Bobby Charlton says Manchester United have not looked into replacements for Sir Alex Ferguson because the Scot could be in charge at Old Trafford for another decade.

Ferguson, 71, is on course to claim his 13th Premier League title at United this season, and although plenty of top managers have been touted as potential candidates for the job, including Pep Guardiola, Jose Mourinho and David Moyes, Charlton insists there is no rush from inside the club due to Ferguson's longevity.

When asked if United have begun to look at replacements for Ferguson, Charlton told talkSPORT: "No, we've not, because it's just a waste of time.

"It could be next week [when he retires], it could be ten years, it doesn't matter. We will wait for him. We can't tell him what to do, he is fantastic.

"He loves the game and every time he thinks about retiring he has to look carefully at what decision he is making because it is a tough thing for him to do. He is so positive and knowledgeable about the game that he won't make any mistakes. If he retires, it will be his [decision]. He is the greatest thing that has ever happened to our club."

Asked for his thoughts on the England national team, Charlton feels the current side are being hindered by the foreign imports in the Premier League.

"People wonder whether we will ever win it again. I worry about that as well," Charlton, part of the 1966 World Cup winning England team, said.

"When I am asked to give my opinion, I always say yes [we can win the World Cup] but it is a fool's errand. You need good players. But if all the spaces at English clubs are taken by foreign players, you have no chance."